<template>
  <el-form-item :label="label">
    <!-- 进度条 -->
    <el-progress
    type="circle"
    :percentage="precentage"
    :width="178"
    v-if="isUploading"
    :status="precentage === 100 ? 'success' : undefined"></el-progress>
    <el-upload
    v-else
    class="avatar-uploader"
    action="https://jsonplaceholder.typicode.com/posts/"
    :show-file-list="false"
    :on-success="handleAvatarSuccess"
    :before-upload="beforeAvatarUpload"
    :http-request="handleUpload">
      <img v-if="previewUrl" :src="previewUrl" class="avatar">
      <i v-else class="el-icon-plus avatar-uploader-icon"></i>
    </el-upload>
  </el-form-item>
</template>

<script>
import { uploadCourseImage } from '@/services/course'
export default {
  name: 'CourseImage',
  props: {
    value: {
      type: String
    },
    label: {
      type: String
    },
    limit: {
      type: Number,
      default: 2
    }
  },
  data () {
    return {
      isUploading: false,
      // 用于保存进度百分比
      precentage: 0
    }
  },
  methods: {
    // 图片上传处理函数
    async handleUpload (option) {
      this.isUploading = true
      const fd = new FormData()
      fd.append('file', option.file)
      // 发送请求
      const { data } = await uploadCourseImage(fd, (event) => {
        this.precentage = Math.floor(event.loaded / event.total * 100)
      })
      if (data.code === '000000') {
        this.$emit('input', data.data.name)
        this.$message.success('上传成功')
        this.isUploading = false
        this.precentage = 0
      }
    },
    // 上传图片成功
    handleAvatarSuccess (res, file) {
      this.imageUrl = URL.createObjectURL(file.raw)
    },
    // 上传图片前的回调
    beforeAvatarUpload (file) {
      const isJPG = file.type === 'image/jpeg'
      const isLt2M = file.size / 1024 / 1024 < this.limit

      if (!isJPG) {
        this.$message.error('上传头像图片只能是 JPG 格式!')
      }
      if (!isLt2M) {
        this.$message.error('上传头像图片大小不能超过 2MB!')
      }
      return isJPG && isLt2M
    }
  },
  computed: {
    previewUrl () {
      return this.imageUrl || this.value
    }
  }
}
</script>

<style lang='scss' scoped>
::v-deep .avatar-uploader .el-upload {
  border: 1px dashed #d9d9d9;
  border-radius: 6px;
  cursor: pointer;
  position: relative;
  overflow: hidden;
}
::v-deep .avatar-uploader .el-upload:hover {
  border-color: #409EFF;
}
.avatar-uploader-icon {
  font-size: 28px;
  color: #8c939d;
  width: 178px;
  height: 178px;
  line-height: 178px;
  text-align: center;
}
.avatar {
  width: 178px;
  height: 178px;
  display: block;
}
</style>
